Structure-Borne Sound

Abstract

The field of structure-borne sound is more complex than fluid acoustics due to the manifold possible degrees of freedom for force and torque and corresponding elastic reactions. In contrast to fluids, solids can react with elastic forces to pure deformation. The number of possible waveforms is therefore higher. And these waveforms can interact and exchange energy, depending on the geometric and elastic coupling in the specific shape of the solid body. Structure-borne sound plays a very important role in building acoustics, in noise control and in vehicle acoustics, for instance. The characterization of structure-borne sources is a very complex field, too. The dynamic behaviour of the source coupled to the structure must be known. Even in the geometrically simple case of a point-like force source, the elementary parameters of the source can be complex since they are related to real and ideal force sources and inner impedances, similar to electric models of voltage sources acting on electric networks. The power output then not only depends on the source itself but also on the kind of attached structure and the impedance coupling between source and structure.